Can I deduct the HELOC interest I paid in 2020 (at least for the portion of the year it was rented)?
You can deduct a portion of it on SCH A for the period of time it was your primary residence, and a portion of it on SCH E for the period of time it was classified as a rental. Tracing rules still apply. This is covered in IRS Pub 535 Chapter 4 here Start at "Allocation of Interest" bottom of middle column.
